<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    html{
      font-size: 16px;
    }
    .con{
      font-size: 62.5%; 
      /* 10px */
    }
    .text-group{
      font-size: 1.4em;
      /* 14px */
    }
    .text1{
      font-size: 1em;
      /* 14px */
    }
    .text2{
      font-size: 1rem;
      /* 16px */
    }
  </style>
</head>
<body>
  <span class="text2" >文本2</span>
  <br>
  <div class="con" >
      <div class="text-group" >
          <span class="text1">文本1</span>
          <span class="text2" >文本2</span>
    </div>
  </div>



    
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  </script>
</body>
</html>